Electrical water heaters of the domestic type comprise a tank in which is mounted two or sometimes three resistive heating elements disposed at different levels to heat water. The resistive heating elements are controlled by respective thermostats which have set point temperature values whereby to control the temperature of the water inside the tank at different levels. The thermostats have a control portion and a switching portion to switch the resistive heating elements on and off by allowing and cutting the power supply thereto depending on the temperature of the water in relation to the set point temperature of the thermostats. The power supply wiring is usually through a control box mounted on top of the water heater or through a port in the outer wall of the casing with the wiring extending along the tank wall to the thermostats. The wiring is usually held in place by the foam insulation which is injected between the tank and the outer casing mounted spaced about the tank. Foam dams prevent the injected insulating foam material from propagating into the space surrounding the thermostats and the resistive heating elements whereby to form an access space for servicing and adjustment of the set point temperature of the thermostat. The thermostat is provided with several terminals and the power supply wires are connected to specific ones of these. An access door is removably secured to the outer casing for access to each thermostat and resistive heating element.
With the advent of more intelligent water heaters it is necessary to mount electronic devices on such water heaters during fabrication and install associated wiring to control the operation of the electric water heater. Although these electronic devices are mounted in housings it is necessary to provide access thereto for trouble shooting and repair. Accordingly, because these housings are exteriorly mounted they are exposed to environmental conditions, such as dust, humidity, water infiltration and are succeptable to physical damage during installation of the water heater. They are also unsightly and occupy space.
Because intelligent water heaters are progressing quickly, new control devices are continuously being developed by various manufacturers, suppliers and utility providers and the benefit of such more intelligent water heaters can more easily be obtained by the purchasing of a new water heater. Accordingly, existing water heaters cannot benefit from this new technology unless these are modified on site to adapt new control devices thereto. Such modifications are very costly to the consumer or the utility and most will not bear such cost although there is a saving to them by consuming less electricity. Also, depending on the physical location of the water heater the adaption of new control hardware and wiring is often left to the installer to decide how it will be mounted and sometimes resulting in wiring exposed outside the water heating unit and controls being mounted on the outer casing at various locations and sometimes on an adjacent wall of the building structure.